The Geography of Homes Built on Private Wells and with Individual Septic Systems

NAHB Economics analysis of the Survey of Construction (SOC) data shows that less than 9% of new single-family homes started in 2015 are served by individual wells and close to 16% have private septic systems. These shares, however, vary widely across the nine Census divisions with the corresponding shares reaching 39% and 47% in New England – the highest occurrence rates in the nation.

The SOC classifies sewage disposal systems as public sewers (including community or shared sewage/septic systems) and individual septic systems. Most of new single-family homes (84%) are serviced by public sewers. The incidence of individual septic systems among new single-family starts varies by region.

Close to a half of new single-family homes started in New England have private septic systems, while the national share barely reaches 16%. Individual septic systems are also relatively common in the East South Central division (41%) and East North Central division where one in four homes started in 2015 have a private septic system. The share of private septic systems is close to the national average in the Middle Atlantic division where it exceeds 15%.

The common sources of water supply also differ noticeably by geographic location. Similarly to sewage/septic systems, the SOC classifies community or shared water supply/wells as public rather than individual wells. Nationally, close to 9 percent of new single-family homes started in 2015 are served by individual wells, and the remaining vast majority of new homes are served by a public water system, including shared water wells.

In New England, where new homes sit on nation’s largest lots and are more likely to be custom-built, 39% of new single-family homes are built on individual wells. The reliance on private wells is also relatively common in the East North Central where more than a quarter of new single-family homes started in 2015 are built on individual wells. The Middle Atlantic divisions registered the third highest share of homes built on individual wells, 12% – still exceeding the national average of 8.6%.

In contrast, individual wells that are not shared are almost non-existent in the East South Central and West South Central divisions where their shares are around 2%.